Kedinger Valerie, Sansregret Laurent, Harada Ryoko, Vadnais Charles, Cadieux Chantal, Fathers Kelly, Park Morag, Nepveu Alain
McGill University Cancer Pavilion, McGill University, Montreal, Quebec H3A 1A3, Canada.
J Biol Chem. 2009 Oct 2;284(40):27701-11. doi: 10.1074/jbc.M109.031849. Epub 2009 Jul 27.
In this study, we investigated the mechanism by which the CUX1 transcription factor can stimulate cell migration and invasion. The full-length p200 CUX1 had a weaker effect than the proteolytically processed p110 isoform; moreover, treatments that affect processing similarly impacted cell migration. We conclude that the stimulatory effect of p200 CUX1 is mediated in part, if not entirely, through the generation of p110 CUX1. We established a list of putative transcriptional targets with functions related to cell motility, and we then identified those targets whose expression was directly regulated by CUX1 in a cell line whose migratory potential was strongly stimulated by CUX1. We identified 18 genes whose expression was directly modulated by p110 CUX1, and its binding to all target promoters was validated in independent chromatin immunoprecipitation assays. These genes code for regulators of Rho-GTPases, cell-cell and cell-matrix adhesion proteins, cytoskeleton-associated proteins, and markers of epithelial-to-mesenchymal transition. Interestingly, p110 CUX1 activated the expression of genes that promote cell motility and at the same time repressed genes that inhibit this process. Therefore, the role of p110 CUX1 in cell motility involves its functions in both activation and repression of transcription. This was best exemplified in the regulation of the E-cadherin gene. Indeed, we uncovered a regulatory cascade whereby p110 CUX1 binds to the snail and slug gene promoters, activates their expression, and then cooperates with these transcription factors in the repression of the E-cadherin gene, thereby causing disorganization of cell-cell junctions.
在本研究中，我们探究了CUX1转录因子刺激细胞迁移和侵袭的机制。全长p200 CUX1的作用比经蛋白水解加工的p110亚型弱；此外，影响加工过程的处理对细胞迁移的影响类似。我们得出结论，p200 CUX1的刺激作用即使不是完全通过p110 CUX1的产生介导的，至少也是部分通过其介导的。我们建立了一份与细胞运动相关功能的推定转录靶标清单，然后在一个迁移潜能受到CUX1强烈刺激的细胞系中，鉴定出那些其表达直接受CUX1调控的靶标。我们鉴定出18个基因，其表达直接受p110 CUX1调控，并且在独立的染色质免疫沉淀试验中验证了其与所有靶标启动子的结合。这些基因编码Rho-GTPases的调节因子、细胞间和细胞与基质的粘附蛋白、细胞骨架相关蛋白以及上皮-间质转化的标志物。有趣的是，p110 CUX1激活促进细胞运动的基因的表达，同时抑制抑制该过程的基因。因此，p110 CUX1在细胞运动中的作用涉及其在转录激活和抑制方面的功能。这在E-钙粘蛋白基因的调控中得到了最好的例证。事实上，我们发现了一个调控级联，其中p110 CUX1结合蜗牛和蛞蝓基因启动子，激活它们的表达，然后与这些转录因子协同抑制E-钙粘蛋白基因，从而导致细胞间连接的紊乱。
